Server-side events as configuration (#1871)

Co-authored-by: Fons van der Plas <fonsvdplas@gmail.com>

src/Configuration.jl

@@ -62,6 +62,7 @@ The HTTP server options. See [`SecurityOptions`](@ref) for additional settings.
     notebook::Union{Nothing,String,Vector{<:String}} = nothing
     init_with_file_viewer::Bool = false
     simulated_lag::Real = 0.0
+    on_event::Function = function(a) #= @info "$(typeof(a))" =# end
 end
 
 """

src/notebook/Events.jl

@@ -9,37 +9,36 @@ the FileSaveEvent may be triggered whenever pluto wants to make sure the file is
 which may be more often than the file is actually changed. Deduplicate on your own if
 you care about this.
 
-To use that, we assume you are running Pluto through a julia script and
-opening it as 
-
-julia > pluto_server_session = Pluto.ServerSession(;
-    secret = secret,
-    options = pluto_server_options,
-)
-
 Define your function to handle the events using multiple dispatch:
 
 First assign a handler for all the types you will not use, using the supertype:
 
-julia >    function myfn(a::PlutoEvent)
-        nothing
-    end
+```julia-repl
+julia> function myfn(a::PlutoEvent)
+            nothing
+        end
+```
+
 
 And then create a special function for each event you want to handle specially
 
-julia >    function myfn(a::FileSaveEvent)
-        HTTP.post("https://my.service.com/count_saves")
-    end
+```julia-repl
+julia> function myfn(a::FileSaveEvent)
+            HTTP.post("https://my.service.com/count_saves")
+        end
+```
 
-Finally, assign the listener to your session
+Finally, pass the listener to Pluto's configurations with a keyword argument
 
-julia > pluto_server_session.event_listener = yourfunction
+```julia-repl
+julia> Pluto.run(; on_event = myfn)
+```
 """
 abstract type PlutoEvent end
 
 function try_event_call(session, event::PlutoEvent)
     return try
-        session.event_listener(event)
+        session.options.server.on_event(event)
     catch e
         @warn "Couldn't run event listener" event exception=(e, catch_backtrace())
         nothing

src/webserver/MsgPack.jl

@@ -31,6 +31,10 @@ MsgPack.msgpack_type(::Type{Configuration.CompilerOptions}) = MsgPack.StructType
 MsgPack.msgpack_type(::Type{Configuration.ServerOptions}) = MsgPack.StructType()
 MsgPack.msgpack_type(::Type{Configuration.SecurityOptions}) = MsgPack.StructType()
 
+# Don't try to send callback functions which can't be serialized (see ServerOptions.event_listener)
+MsgPack.msgpack_type(::Type{Function}) = MsgPack.NilType()
+MsgPack.to_msgpack(::MsgPack.NilType, ::Function) = nothing
+
 # We want typed integer arrays to arrive as JS typed integer arrays:
 const JSTypedIntSupport = [Int8, UInt8, Int16, UInt16, Int32, UInt32, Float32, Float64]
 JSTypedInt = Union{Int8,UInt8,Int16,UInt16,Int32,UInt32,Float32,Float64}

src/webserver/Session.jl

@@ -47,7 +47,6 @@ Base.@kwdef mutable struct ServerSession
     secret::String = String(rand(('a':'z') ∪ ('A':'Z') ∪ ('0':'9'), 8))
     binder_token::Union{String,Nothing} = nothing
     options::Configuration.Options = Configuration.Options()
-    event_listener::Function = function(a::PlutoEvent) #= @info "$(typeof(a))" =# end
 end
 
 function save_notebook(session::ServerSession, notebook::Notebook)

test/Events.jl

@@ -12,7 +12,8 @@ import UUIDs: UUID
         @info "this run!"
         push!(events, typeof(a))
     end
-    🍭 = ServerSession(; event_listener = test_listener)
+    🍭 = ServerSession()
+    🍭.options.server.on_event = test_listener
     🍭.options.evaluation.workspace_use_distributed = false
 
     fakeclient = ClientSession(:fake, nothing)